Preterm infant behavioral and heart rate responses to antenatal phenobarbital

The effects of antenatal phenobarbital on behavioral state and heart rate ( HR) were examined in a randomized sample of 49 preterm infants > 24 and < 3 4 weeks postconceptional age. Behavioral state and HR observations were mad e during a routine care giving procedure on Days 1, 2, and 3 of life. There were no differences in behavioral state and HR responses between control a nd experimental subjects, suggesting that antenatal phenobarbital did not h ave a sedative effect on experimental subjects. Infants in both study group s responded to caregiving with changes to fussy/cry behavior and increases in HR. Older infants and nonventilated infants were more often in fussy/cry states during care giving than younger infants and ventilated infants. The HR increases were not clinically important, but the behavioral changes wer e, suggesting that behavioral response may be a more sensitive sign of dist ress than HR in very young preterm infants. (C) 1999 John Wiley & Sons, Inc . Res Nurs Health 22:461-470, 1999.